Rotary valves are used in a variety of different industries, including the pharmaceutical, chemical and food industries. A rotary valve is usable to transfer fluids, powders or granular substances from one stage of a processing line to another.
A typical rotary valve comprises a casing, which has an upper inlet and a lower outlet, in which a rotor comprising a rotor shaft and vanes is housed. Solid bulk product may be conveyed through the rotary valve with the assistance of a gas (typically air) pressure differential.
A rotary valve may be used to control the rate of flow of a product, and may have an explosion/flame-containment design. To achieve high sealing and feeding efficiency, the clearance between the rotor vanes and the casing must be maintained within a narrow tolerance range. However it is usual for the rotor to be removed regularly from the casing, to allow cleaning. A problem exists with maintaining proper alignment of the rotor when the rotor has been removed from, and is to be subsequently replaced in, the casing.
A type of rotary valve is known in which an end portion of the rotor shaft is supported within a bearing assembly of a removable end plate of the casing, the removable end plate being coupled with a pair of guide rails that are slidably coupled to the main body of the casing. This arrangement allows the rotor to be conveniently withdrawn from, and inserted into, the interior of the casing, by slidably moving the removable end plate of the casing away from, and towards, the interior of the casing, respectively. The guide rails serve to facilitate movement of the rotor and to maintain the rotor in an aligned position relative to the interior of the casing. However, a problem exists with ‘drop’ or ‘downward pitch’ of the rotor shaft from the ideal level orientation, which is experienced when the rotor shaft is supported at a single end only within the removable end plate of the casing.
It is an object of the present invention to provide a rotary valve with improved rotor alignment features.